I can't really tell can it be allergy maybe, new food or washing powder or anything else that has changed? I'm sure someone will jump in that has experience with things like this. Hope your lill boy feels better soon
Did you just get him? If so, its probably a rash from the grass. Ours had the same thing for the first few weeks after we got them home. He will outgrow it.
Harlea had a similar rash when we brought her home. Some was nicks and scrapes from her litter mates the rest was from lying I the grass. Chlorohexidine spray or some coconut oil rubbed on the area will provide relief and assist with healing.
Otis will get little places like this when he has a flea. We live in Tennessee and our outside dog will give Otis a flea from time to time. Otis just had one a few weeks ago.
Remi gets this type of rash when he runs through long grass or has a food allergy. When we switched him to Fromms and went 25 old food to 75 new food, the rash definitely sprang up. We take care of this by bathing him in anti-septic shampoo, like Duoxo, and giving him a Benedryl. And of course stopping whatever caused the allergy.